1. Field of the Invention
The present invention relates to an emergency device for energizing electrically powered gear-shifters in a transmission, in an emergency.
2. Description of the Prior Art
Typically, but not exclusively, the gear-shifters for fully or partially automated mechanical type transmissions are nowadays powered by pneumatic high and low (or exhaust) pressure sources controlled by solenoids.
Transmissions, especially on heavy vehicles, are shifted in ratio by such driving means in order to take the effort of gear-shifting away from the driver or operator. The transmission may be entirely automatic, wherein all shifting activity, including synchronization and decisions to shift, as to when and into which ratio, are all totally automatic. The transmission may be semi-automatic, where the shift decisions are manual but most or all of the accomplishment of the shifting is automatic. Alternatively, the transmissions may be power assisted wherein only the shifting from one ratio to the other may be powered, i.e. shifts are manual, but are assisted by the electrically controlled pneumatic powering. The invention is concerned with enabling a driver to select one reverse and at least one forward ratio of those normally available, whenever the usual electronic computer unit (ECU) or multi-wired distributor has failed or is distrusted but when there can still be hope that the electric drivers are still operative. Hereinafter this specification considers only electrically selected and electrically controlled shifting, however the electrical selection signals are generated and distributed, and whatever pneumatic or other electromechanical device may relay the electrical signals into power for shift-driving. Presently preferred embodiments comprise solenoid-controlled pneumatic powered shifters of the type sometimes called "X-Y" shifters or drivers.
The invention is not therefore concerned with the oil powered (non-electrical) automatic transmissions typical of today's automobiles.